Terror management theory posits that close relationships assuage existential mortality concerns because they foster attachment-based felt security, enhance self-esteem, and validate shared cultural worldviews. However, the relative buffering influence of these mechanisms remains relatively unknown and has sparked theoretical debate. Some theorists argue that felt security is central, whereas others suggest it does not offer unique protection from death awareness, independent of self-esteem and worldview validation. We conducted two experiments to clarify felt security’s role. Testing felt security on its own, it significantly mediated the association between death awareness and increased intimacy striving (Study 1). However, when tested alongside relational self-esteem and worldview validation, felt security again exerted a significant mediating effect in parallel with relational self-esteem, although only among female participants (Study 2). These results provide initial support for the subordinate tripartite model and functional independence claim put forth in recent years. We discuss the implications of these findings.